MIPS: Reserve space for relocation table (069fd766) · Commits · 戴 / test

When CONFIG_RELOCATABLE is enabled, add a new section in the memory map to be filled with relocation data. CONFIG_RELOCATION_TABLE_SIZE allows the amount of space reserved to be adjusted if necessary. The relocs tool will populate this reserved space with relocation information. The space is reserved within the elf by filling it with 0's, and an invalid entry is left at the start of the space such that kernel relocation will be aborted if the table is empty. Signed-off-by:

Matt Redfearn <matt.redfearn@imgtec.com> Cc: Aaro Koskinen <aaro.koskinen@nokia.com> Cc: David Daney <ddaney@caviumnetworks.com> Cc: Jonas Gorski <jogo@openwrt.org> Cc: linux-mips@linux-mips.org Cc: kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/12982/ Signed-off-by:

Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

+16 −0

Original line number	Diff line number	Diff line
		@@ -2473,6 +2473,22 @@ config NUMA
		config SYS_SUPPORTS_NUMA
		bool

		config RELOCATION_TABLE_SIZE
		hex "Relocation table size"
		depends on RELOCATABLE
		range 0x0 0x01000000
		default "0x00100000"
		---help---
		A table of relocation data will be appended to the kernel binary
		and parsed at boot to fix up the relocated kernel.

		This option allows the amount of space reserved for the table to be
		adjusted, although the default of 1Mb should be ok in most cases.

		The build will fail and a valid size suggested if this is too small.

		If unsure, leave at the default value.

		config NODES_SHIFT
		int
		default "6"

arch/mips/kernel/vmlinux.lds.S

+21 −0

Original line number	Diff line number	Diff line
		@@ -136,6 +136,27 @@ SECTIONS
		#ifdef CONFIG_SMP
		PERCPU_SECTION(1 << CONFIG_MIPS_L1_CACHE_SHIFT)
		#endif

		#ifdef CONFIG_RELOCATABLE
		. = ALIGN(4);

		.data.reloc : {
		_relocation_start = .;
		/*
		* Space for relocation table
		* This needs to be filled so that the
		* relocs tool can overwrite the content.
		* An invalid value is left at the start of the
		* section to abort relocation if the table
		* has not been filled in.
		*/
		LONG(0xFFFFFFFF);
		FILL(0);
		. += CONFIG_RELOCATION_TABLE_SIZE - 4;
		_relocation_end = .;
		}
		#endif

		#ifdef CONFIG_MIPS_RAW_APPENDED_DTB
		__appended_dtb = .;
		/* leave space for appended DTB */

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